Fast Memory Capture (version 1.3)
- Michael Abbott
Analytics
This screen shows the status and configuration of the fast memory capture system.
For direct access to the full memory buffer, see Matlab Fast memory readout for the Matlab interface, or Socket Fast memory readout for the underlying socket API.
All PVs below are prefixed with $(device).
Two graphs are shown at the top:
| Title | PV | Description |
|---|---|---|
| Channel 0, Channel 1 | :MEM:WF0, :MEM:WF1 | Window into data captured on channels 0 and 1. The starting point of the window is determined by the :MEM:OFFSET_S field, but for reading large amounts of data the Direct Memory Access API is recommended. |
The selection is controlled by three interacting PVs. Data can be captured from ADC, FIR, or DAC data from either axis, and two channels of bunch by bunch data can be captured at any time.
| Title | PV | Description |
|---|---|---|
| Channel 0, Channel 1 | :MEM:SEL0_S, :MEM:SEL1_S | These two PVs allow the channel selection to be configured one channel at a time, but the true selection pattern is shown to the right. These two PVs will rewrite each other as necessary to ensure that the selection is always consistent. |
:MEM:SELECT_S | This is the true selection of which data source will be captured into which channel. |
The ADC and DAC sources can be selected, and their control PVs are copied here:
| Title | PV | Description |
|---|---|---|
| ADC X, ADC Y | :ADC:DRAM_SOURCE_S | Source of ADC data, configured on ADC Setup page. |
| Fill reject length | :ADC:REJECT_COUNT_S | Length of fill reject filter, configured on ADC Setup page. |
| DAC X, DAC Y | :DAC:DRAM_SOURCE_S | Source of DAC data, configured on DAC Setup page. |
The dynamic range of the FIR filter is much higher than will fit into the 16-bit capture memory, so the gain for captured FIR can be managed:
| PV | Description |
|---|---|
:MEM:FIR0_GAIN_S, :MEM:FIR1_GAIN_S | The top 16-bits (gain of 0dB) or the bottom 16-bits (gain of +54dB) can be selected for data capture for each axis. |
:MEM:FIR0_OVF, :MEM:FIR1_OVF | When the FIR gain is set to +54dB this indicator will show an alarm if overflow will occur during capture of the FIR data for this axis. |
The remaining PVs are used for general control.
| Title | PV | Description |
|---|---|---|
| View offset | :MEM:OFFSET_S | This programs the start point of the two channel readout waveforms in turns relative to the trigger point. |
| Runout | :MEM:RUNOUT_S | This configures how much data is captured into memory after a trigger is seen, and can be set to 12.5%, 25%, 50% or 99.5% of the available 2GB. Note that memory capture treats the capture memory as a large circular buffer, and once armed capture continues until a trigger occurs, after which the number of samples configured here are captured. |
| Capture | :MEM:CAPTURE_S | This initiates an untriggered round of memory capture. |
| Capture status | :MEM:BUSY | When capture is armed this indicates busy, and indicates Ready when data is captured and ready to be read out. |